Ultraviolet radiation has been successfully used in purification and sterilization systems for various media, such as air, water, and food. Such a system includes a source of ultraviolet radiation that emits ultraviolet radiation having wavelength(s) close to the absorption peaks of biologically significant molecules of deoxyribonucleic acid (DNA) and proteins. The system sterilizes the media by exposing it to ultraviolet radiation of a sufficient power and for a sufficient exposure time to destroy the internal biomolecular structure of bacteria, viruses, protozoa, and other organisms, which may be present in the media.
Typically, the source of the ultraviolet radiation in an ultraviolet purification or sterilization system is a mercury lamp. To this extent, a low-pressure or a medium-pressure mercury lamp provides a linear spectrum of radiation with one or more peak lines having a wavelength that is in the relative vicinity to the DNA absorption line. For example, a low-pressure mercury lamp having a main peak at 253.4 nanometers (nm) is generally used in low-consumption residential water purification systems and residential air purification systems. Further, a medium-pressure mercury lamp having a higher radiation power and a multi-peak radiation spectrum is used in municipal systems with medium and high water consumption.
However, the use of a mercury lamp as the source of ultraviolet radiation has significant drawbacks. For example, mercury is an extremely dangerous element, thereby limiting the applications of mercury-based water and/or air purification systems. In particular, such a mercury-based water purification system is generally not used in transportation or individual applications. Further, a typical lifetime of the mercury lamp generally does not exceed ten thousand hours. Still further, the radiation spectrum of the ultraviolet radiation generated by the mercury lamp includes peak lines having characteristic wavelengths that do not exactly coincide with the absorption peaks of DNA and proteins and these peak lines cannot be controlled or adjusted, which results in a decrease in the efficiency of the system. Still further, mercury lamps are fragile and often bulky, which generally adds to the overall cost and/or size of the system and does not allow for a flexible design. Various other limitations are present as will be recognized by one of ordinary skill in the art.